Standards of wireless communication to use the same frequency band as that of a television broadcast being a licensed business and to be capable of being operated with no such a license, have been investigated. In these standards, a television broadcaster is regarded as a primary user, and only when a licensed frequency band of the primary user is not used, a secondary user is allowed to operate wireless communication in the frequency band (the licensed frequency band that is not used=white space).
In order to confirm that no TV signals exist, a communication device being the secondary user used under such an environment inquires of a dedicated database about TV channels, for example. That is, current position information of the communication device is transmitted to the database, and a list of frequencies available (effective) at the position is obtained from the database. Then, a frequency to be used is selected from the frequencies of the list and as the secondary user, wireless communication is operated.
On the other hand, as one embodiment of the secondary user, there is conceived an embodiment in which a plurality of communication devices are connected to one another in a manner to form a mesh, and even when only one of the communication devices has a function to communicate with the Internet and the like, all the communication devices can be connected to the Internet and the like through a meshed network. Further, as long as the plurality of communication devices form a mesh as above, when these communication devices perform communication with one another, the communication is completed in the network (the mesh network), so that it is efficient.
With regard to the secondary users that can form a mesh network, management for maintaining the mesh network is required, and further, communication is performed by using the white space, so that management for the communication is also required. Particularly, it is conceived that well maintaining communication qualities while accommodating a change in momentarily changeable communication environment is important for the secondary users capable of forming a mesh network in the white space.